Is the emergence of life so stupendously unlikely it may have happened only once in the history of the universe? Or is “life” written into the basic laws of physics?
A great deal rides on the answer. If life is a near-miracle, then we are probably alone in the vastness of the universe, a freakish and irrelevant sideshow in a great impersonal cosmic drama. But if, to use the words of Belgian biologist Christian de Duve, life is a “cosmic imperative” – almost bound to arise under Earth-like conditions – then the universe should be teeming with it. And if the laws of nature are rigged in favour of life, we can regard our own existence as a natural and integral part of the unfolding cosmic scheme.
On philosophical grounds, people often prefer one alternative to the other. The first view presents us with the stark loneliness of cosmic irrelevance, ameliorated by the knowledge that we alone carry the spark of reason. The second is a picture of a cosmic playground in which life’s richness is manifested across the universe, but in which humans are most likely biological also-rans.
But in science, philosophical prejudice is no substitute for hard facts. And, as the following four features show, the facts are on their way.
